Half to william robinson



'(Nomoael.) J E. GREENAYWALT.

OXIDIZIN G FURNAGE.

- 10.551,725. Patented Dec.17,1895.

ATTORNEY UNITED; STATES PATENT OFFICE.

JOHN ECKERT GREENAVALT, OF DENVER, COLORADO, nASSIGNOR OF ONE- HALF TO VILLIAM ROBINSON, OF SAME PLACE.

`OXIDIZINC-FURNACE.

SPECIFICATION forming part of Letters Patent No. 551,725, dated December 17, 1895. Application filed April 9, 1894. Renewed March 19, 1895. Serial No. 542,417. (No model.)

figures of reference marked thereon, which form a part of this specification.

My inventionA relates to improvements in oxidizing-furnaces.

The objectof this invention is the econom-l ical preparatory treatment of refractory ores by the thorough and perfect oxidization of a'll objectionable elements, whereby all the gold is freed from its intimate mechanical and chemical combinations, disassociated from other metals or impurities, and left in a porous, malleable and clean condition, thus insuring successful amalgamation when the gold is brought in contact with the mercury.

When a refractory gold ore is oxidized in furnaces of such construction that the fuel gases are allowed to come in contact with the ore, the gold, although liberated, will not amalgamate readily, owing to the fact that the reducing gases of the furnace change some of the elements to the metallic state, in which condition they are readily absorbed or combined by or with the gold, forming an alloy which prevents the amalgamation of the gold except by long and continuous grinding in contact with mercury, and for the further reason that the gold becomes coated with a film of carbonaceous matter or metallic oxides, which prevents the gold from uniting with the mercury.

Most gold ores carry some objectionable elements, such as sulphur, arsenic, antimony, lead or zinc. These compounds, in the presence of the reducing gases and carbonaceous matter from the furnace, are frequently reduced, thus liberating the objectionable elements which form an alloy with the gold, producing a compound which amalgamates with the greatest difficulty. This is especially true of the ores containing arsenic and antimony, since the presence of either of these metals in the proportion of one part in a thousand will render the gold so brittle that it is incapable 5 5 of being absorbed or attacked by the mercury. Therefore, inthe preparation of ore for amalgamation, it is very essential to the successful extraction of gold to prevent the ore from coming in contact with the fuel gases. This 6o l accomplish in my improved furnace by keeping the ore under treatment in a chamber entirely distinct from that occupied by the fuel gases. The film of oxide lis entirely broken up and the gold completely released from any mechanical casing or covering by dropping the treated ore into an upward spray of water, which disintegrates the entire mass and reduces it to a ne powder.

In my improved furnace the necessary heat 7o in the munie-compartment to carry out the process of oxidization is obtained from three sources-namely, that transmitted through the wall of the muffle-chamber from the combustion-gases which proceed from the fire- 7 5 place, that introduced by the superheated air, and that produced by the oxidization of the combustible elements of the ore, especially Y Sulphur.

In the case of ores carrying a large per- 8o centage of sulphur, very little extraneous heat is necessary in carrying out the oxidizing process.

In the oxidization of ores containing zinc the-loss byvolatilization is almost eliminated, 8 5 owing to the fact that the zinc is not transformed to the metallic condition, and therefore not volatilized, since the oxide of zinc is not volatile.

My improved oxidizing mufle and gold- 9o cleansing furnace will be fully understood by reference to the accompanying drawings, in which is illustrated an embodimentV thereof.

In the drawings, Figure l is a vertical longitudinal section taken on the line x Qc, Fig. 2. Fig. 2 is a section taken on the line n fn, Fig. l. Fig. 3 is a horizontal section taken on the line w w, Fig. 2. Fig. 4 is a vertical section taken on the line y y, Fig. 2. Fig. 5 is a horizontal section taken on the line o r, roo Fig. l. Fig. 6 is a horizontal sectiontaken throughthe munie-compartment and the surrounding flues, the construction being shown on a larger scale.

Similar reference characters indicate corresponding parts or elements in all the views.

Referring now to the views, the furnace consists essentially of a tower 5 containin g a vertical mufiie-compartment (i surrounded by vertical flues 7 for heating the exterior surface of the -muille-wall S, and a suitable combustion-chamber 9 containing a series of flues 10 for heating the air necessary for the oxidization of the objectionable elements contained in the orc.

The munie-compartment 6 containsfa series of inclined shelves or slabs 13 alternately arranged one above another on opposite sides of the wall S, and so placed 'that one discharges its ore upon the next lower shelf on the opposite side of vthe chamber, and so on. Hence, the pulverized ore carried upward by a suitable elevator 12 and discharged in a thin stream into the top of the mnfiie'eompartment or chamber (5 engages and rolls over each pla'te or shelf in succession in its downward course.

The inclined shelves 13 are supported by vertical columns 1l, which form vertical partitions separating the space around the wall of 4the munie-chamber into the separate vertical `t1ues 7 and projectingslightly into the munie-compartment for the purpose stated. This manner of supporting the shelves is shown in Fig. G. p

The wall 8 inclosing the muftle-ehamber containing this series of shelves is composed of thin slabs of some mineral substance, as nre-clay, capable of withstanding a high degree of heat, and which will not be attacked by the eorroding gases of thefu'rnace. Thus, the ore in its descent, is completely isolated from 'the 'fuel gases, and never comes in contact with them during its treatment, whereby the oxidized product is Afree from these deleterious iniiuences. The thin wall Sis prefer ably supported by the columns 1l he'reinbefore mentioned in connection with the shelves 13, which they support, thus relieving the wall 8 of the strain incident to said support.

The fuel gases pass upward 'through the vertical 'nues 7 and on the outside of thethin wallS, through which the heat from the `combustion-chamberyis readily conveyed to the interior of the wall, or into the inutile-compartment.

The ore, in its downward course, meetsthe highly-heated air containing oxygen in a pure and 'highly-active condition, thus producing in the glowing-chamber an intensely-oxidizing atmosphere, through which it is almost impossible for any particle of ore to pass without bein gperfectly oxidized. This heated air is introduced into the lower end of the munie compartment or chamber, its course from the outside through the furnace being indicated by the feathered arrows. rlhis heated air enters the chamber G immediately after having passed through the incandescent fiues of the combustion-chambers, and without having come in contact with any carbonaceous product or gases.

The descending ore particles gradually entera purer and higher heated atmosphere of oxygen, whereby they are continually losing their refractory character until the culminating point of the process is attained, when the ore meets a large volume oil highly-heated air and loses its last objectionable elements. The ore has now been thoroughly oxidized and freed from its natural impurities, while the gold has been liberated from the mechant cal and chemical combinations without the production of detrimental alloys. The oxidized ore then passes from the ehaniiber 6 through the inclined ilue 15 at the bottom, and thence into the chamber 17 containing an upward spray of cold water issuing from a nozzle 18 connected with any suitable waterforcing apparatus. In this spraying-cham ber the ore particles are thoroughly disintegrated, while all films of oxides covering the gold are removed.

The chamber 17 is provided "at its upper extremity or month 17 l with a fan 20, which,

is typical of any suitable suction-indueing mechanism, whose function is to remove the steam orvapor generated bythe engagement ofthe hot ore with the cold spray of water.

The unfeathered arrows indicate thecourse of the heat from the combustion-chamber to the flues 7 surrounding the loxidizing-chamber.

The feathered arrows indicate the course of the air-currents passing into 'the oxidizing chamber (i.

l claim 1. In an ore roasting furnace, `the combina tion with the combustion chamber, of a vertical oxidizing chamber separated from the combustion chamber, au outer chamber surrounding Athe oxidizing chamber and divided by verticalcolumns int-o ilues connected with the combustion chamber, and air flues located in the combustion chamber and leading to the oxidizing chamber, substantially as described.

2. In a stack oxidizing furnace, the combination with the combustion chamber, of a munie-compartment separated from the combustion chamber and containing inclined shelves arranged one above another and supported on the wall inclosing the compartment, whereby the ore is made to fall from one shelf to another, air iiues located in the combustion chamber and opening into the bottom of the muiiie-eompartment, an outer chamber surrounding the muffie-eompartment and divided by vertical columns into fines connected with the combustion chamber, whereby said fines receive the fuel gases from said chamber, substantially as described.

In `an oxidizing furnace, a munie-compartment or chamber having the linclined IOO IIO

shelves arranged therein and adapted to feed from one `to another, an inclined discharge flue leading from the bottom of the mufflechamber to another chamber, said last named chamber being provided with means for throwing an upward spray of water to meet the falling ore, an auxiliary flue or conduit 17 located outside of the furnace and connected with the spray chamber, and suitable suction inducing mechanism connected with said conduit for drawing off the steam generated by the contact of the hot ore with the water, which steam is thus prevented from passing to the munie-compartment, substantially as described.

4. In an ore roasting furnace, the combination with the combustion chamber, of a vertical oxidizing chamber separated from the combustion chamber, and an outer chamber surrounding the oxidizing chamber and divided by vertical columns into flues which are connected with the combustion chamber, substantially as described.

In testimony whereof I affix my signature in the presence of two witnesses.

JOHN ECKERT GREENAVALT.

Vitnesses:

G. J. ROLLANDET, CHAs. E. DAWSON. 

